One third of Arctic ice cap now missing; Midwestern floods; tropical update

Sea ice in the Arctic continues its record decline, thanks to unusually cloud-free conditions and above-average temperatures. For August 21, the National Snow and Ice Data Center estimated that fully one third of the Arctic ice cap was missing, compared to the average levels observed on that date from 1979-2000. Sea ice extent was 4.92 million square kilometers on August 21, and the 1979-2000 average for the date was about 7.3 million square kilometers. Arctic sea ice has fallen below the record low absolute minimum of 4.92 million square kilometers set in 2005 by about 8%, with another 3-5 weeks of the melting season still remaining. Reliable records of sea ice coverage go back to 1979.

Figure 1. Extent of the polar sea ice on August 21, compared to the average for the date from the 1979-2000 period (pink line). Image credit: National Snow and Ice Data Center.

With one third of the Arctic ice cap already gone, and another month of melting to go, we need to consider what effect this will have on weather, climate, and sea level rise. Well, we don't need to worry about sea level rise, since the polar sea ice is already in the ocean, and won't appreciably change sea level when it melts. However, the remarkable melting of the ice cap will likely lead to unusual weather patterns this fall and winter. The lack of sea ice will put much more heat and moisture into the polar atmosphere, affecting the path of the jet stream and the resultant storm tracks. Expect a much-delayed arrival of winter to the Northern Hemisphere again this year, which may lead to further accelerated melting of the ice cap in future years.

Last week, I remarked that the most recent images from the North Pole webcam show plenty of melt water and rainy conditions near the Pole. It turns out that was misleading, since the webcam is on a ship that was headed towards the pole, but had not reached it. There have been rainy conditions at the Pole this summer, and there is some open water there, but this is not uncommon in summer. Shifting ice frequently opens up leads (cracks) with open sea water at the Pole. It was one of these open leads that British swimmer Lewis Gordon Pugh swam in for 18 minutes this July to draw attention to global climate change.

Midwest floodingTo get an idea of the magnitude of the flooding that has hit the Midwestern U.S. during the past ten days, take a look at the total amount of rain from August 10-22 (Figure 2). We can blame Tropical Storm Erin for the rain in Texas and Oklahoma (up to 11 inches), and for the nine flooding deaths that occurred in those states. However, the unbelievable rain amounts in excess of 20 inches in Minnesota and Wisconsin were primarily due to a frontal system--with the help of some copious moisture pumped northwards by the counter-clockwise circulation around Erin while it spun over Oklahoma.

Tropical updateThere are no threat areas in the Atlantic to discuss. Two of our four reliable forecast models, the NOGAPS and ECMWF, are predicting that a tropical depression could form off the coast of Nicaragua on Sunday. The models forecast that this system would move inland over Nicaragua and Honduras by Monday.

Posted By: KEEPEROFTHEGATE at 3:46 AM GMT on August 26, 2007. has a blob alert been issued yet

THE NHC HAS ISSUED A BLOB ALERT. THERE APPEARS TO BE A BLOB SOMEWHERE IN THE MIDDLE OF THE UNITED STATES CURRENTLY SITTING AT HIS COMPUTER, STARING AT A SCREEN AND BLOGGING ON WEATHER UNDERGROUND. ALTHOUGH THIS BLOB IS NOT EXPECTED TO MOVE FOR THE NEXT DAY OR SO, SOME BREATHING AND POSTING MAY BE POSSIBLE.

Interesting to note here that over the last several runs, the GFS has been persistent indeveloping a troughing patern over the E CONUS and W ATL.

While the GFS has showed breaks in the Atlantic ridge, they have not been persistent. Over the next two weeks, the GFS pattern looks very menacing. If a CV storm does develop in the near term it is quite likely to make landfall somewhere on the North American continent.

2) A protracted heatwave in the SE US supported by an large ridge. (594 hts)

The ridge in 1980 kept hurricane Allen (Cat 5)well to the south with landfall around theTex/Mex border as was the case with Dean.

The rest of the '80 season was mostly fish spinning due to troughing over the W ATL.Interesting to note here that over the last several runs, the GFS has been persistent indeveloping a troughing patern over the E CONUS and W ATL.

"just cyclonic turning" Explain please. Aren't all hurricanes and typhoons "just cyclonic turning". What in your opinion makes the rather disorganized circulation on the continent a better candidate for development than the closed low level circulation off the coast?

Just cyclonic turning meaning that the stratocumulus clouds are turning but it isn't focused on a point. Tonights QuickSat indicated some turning but no closed low. I'm not necessarily greatly interested in one more than the other just a slight increase in interest because 90L, had a mid level circulation before it came of the coast; like this wave coming of the coast.

"just cyclonic turning" Explain please. Aren't all hurricanes and typhoons "just cyclonic turning". What in your opinion makes the rather disorganized circulation on the continent a better candidate for development than the closed low level circulation off the coast?

Lat25Only posted to apply focus to some central issues.Let the debate rage...from there.However I totally agree with your cynicism and real world view of research."

Sorry to beat the horse, but I had to sit here and read that paper you linked again. I really didn't believe it.

That is where some of the people posting on this blog heard that the intensity of cyclones will increase with global warming. This is from the International Workshop on Tropical Cyclones from just last year.

The models that didn't predict what they wanted them to predict, they threw those models out! Talk about padding your bets. They only used the data from the models that fit their agenda.

I posted this linkLinkearlier. According to the barbs, the low off the coast looks much better organized than any of the activity still on the continent. Any thoughts on the divergence of the GFS and CMC models that I referred to in my last post?

Haven't seen anything from Dr. Masters... I hope he wasn't adversely affected by the severe weather in and around Michigan.

Well, if he did, hopefully he came through it OK (Obviously he's seen severe weather before :)) and can tell us about it.

Here's a report of some of the issues in and around Flint, MI today. Storm Report

Interestingly enough, that's one of the few places I ever tried to storm chase... I recommend leaving that to professionals... Or at least make sure you have good doppler radar with you... One word of advice... don't drive through the storm looking for tornadoes.

I was having quite a bit of trouble seeing even before the hail started... It gives someone from California like me new respect for those little red and purple areas on the radar that show up in other states.

When I realized how screwed I was, it took me about 20 minutes to go 1 more mile to the next freeway exit and go back to my hotel.

Another question from a newbie; Is there a consensus of opinion as far as when the peak of hurricane season is? Does the peak have anything to do with La Nina, or El Nino? Hopefully I will become educated and can show off my knowledge to my friends.

The peak doesnt have anything to do with la nina or el nino, although they both either enhance storms or supress them. La nina, enhances storm activity and usually leads to a more active late season. While, El Nino, supresses activity, creating a less active season. 2006 was an el nino year

A comparison of the GFS and CMC models on the the CV low is very interesting. Both show similar development over the next 60 hours at which time the disturbance is at about 40W. At that time there is an interaction with something (I don't know what) that causes the two models to begin a 180 degree divergence. GFS has the low in steady decline from that point on whereas CMC shows rapid development. Anyone have any ideas about what it is that is causing the model divergence.

Another question from a newbie; Is there a consensus of opinion as far as when the peak of hurricane season is? Does the peak have anything to do with La Nina, or El Nino? Hopefully I will become educated and can show off my knowledge to my friends.